Refining of petroleum oils



Aug. 24, 1943. H. c. PAULSEN REFINING OF PETROLEUM OILS Filed Dec. 30, 1941 wn... MN NN .MN

NUS.

W kWm Patented Aug. 24, 1943V e l 12,327,511 v, .REFINING or PETROLEUM ons' r Henry' C. Paulsen, Elizabeth, N. j., `assigner to A l Standard Oil Development Company, a corporationrof Delaware` 'n Y -Application December 30, 1941, Serial No.Y 4.2*4gi356 jl scams. (cuss- 33) This invention is concernedf'with a method of treating petroleum oils to remove suspended lead sulfide from doctor sweetened stocks@V `It is particularly applicable forei'fective removal of minor traces offlead'suliide `remainingsuspended in: light petroleum distillatesnv following a doctor svifreeteffingV operation asu air` improvement over the; common practice of water washing.

tained by washing aV doctor sweetened gasoline with aqueous `solutionsof sodium salt of mere .capto-benzothiazole*and with other solutions:

' The doctorsweeteningprocess involves the formation of-lead sulde which, due to its-finely divided state, settles very slowly aiterthe product is sweetenedhto a Alow` reactive suliurncontent..

Customarily', a final Vwater washing operationl is employed tofreethesweetened oil of remaining suspended-lead sulfide afterf most of the lead sulfide formed-is separated by settling from the losses and torecovera cleansweeten'edprocluct asV free as Ipossible of lead sulfide.` This'water washing procedure has been found ineicient lin removingthe nal'traces offsuspen'ded lead sulfide with practical limitations of time, apparatus, and amount of'washing water, Vresulting'in excessive lead losses, and thus thelead sulfide remaining in the: sweetened stocks'tends'to settle out treatdpilg inforder toV prevent excessive lead v .Example i e Gasoline from av doctor Ysweetening plant obtained at the outlet-,of the second doctor'settlingr drum was treated with 10% by volume of tnewashing solution `.with one minute of agitation.` The sweetened gasoline after only ,water washing` and paper ltering hada copper dish-.gum of 3 andasulfureontent 0fo.092%,`whi1ea vrsimian portion ofthe same gasoline, after being treated with'10% byvolume of sodium salt of niercaptoev benzothiazole solution in Whichnthe concentration of theV mercapto-benzothiazole salt was 10` mg./100 inl.` for leadsulde removal, followed'by paper filtering, had a copper., dish gum Vof': only 2 anda sulfur content of 0.086

Inladidition'to the above-described operation,

aportion of themercapto-benzothiazole salt s`o1`` ution (10.1 ing/100 ml.)was recirculat'ed forty times on portions of the above gasoline to subin-refine'ry'tanks and necessitates periodic clean- Y.

In accordance with the present invention, it

has been found that' thedoctor sweetened petrof 4' d Y leum stocks containing 4suspendedlead' sulde may be effectively freed ofleadsulde bywashing the"sweetened stocks withaqueous solutions metalsalts of mercaptoaryl thiazole compounds, such as the sodium salt of mercapto benzo-thiazole andbits related derivatives. Accordingly, thev preferred Vthiazole.A salts vcontain the. char-p acteristic meta thiazole `function 1 1 Y in "`a Aheterocyclic compound represented by the formula Ar(NSC) SM, wherein A'rrepresents anf arylene-radical, such asthe phenylene radical (06H42) or-a'substituted-benzene ring with sulfur and nitrogen attached to ortho carbon atoms in Vthe aromatic. `nucleus -and linked to the metal shown in the follow':ing`structure:V

`constituent zM through carbon and Irsulfur, as A of salts of thiazole compounds, preferably alkali stantially free it of lead sulfide. After the forty recirculation cycles,` the washing solution was found to be as eective in removing lead sulde from the gasoline as it was in the initial cycle.

v'Inusing the more effective thiazole salt Wash- `ing'solutions for lead sulde removal from sweetened stocks, Athe Yplant procedure may be efficiently carried out by charging the Wash drum.

with about 2000 gallons of said washing solution andwrecirculating the washing solution with small `additions of fresh solution to `replace the small portion rendered ineffective or lost. The precipitated leadsulfide which is effectively removed bythe Vwashing solution mayfbe readily separated by. draw-off in a vsettler and/or a centriu The following-examples present results ob-LV 55 fugingoperation4 to be `returned to a regenerator in the doctor treating system. Y

In thevaccompanying drawing is shown a ow diagrammatic view of a typical and suitable plant set-up for the doctorv sweetening and washing 3 operations.V

' Inthe drawing, numeralfl'indicat'es a feed inlet line `for the isour gasoline or light petroleum stock containing mercaptans,` which is to be subjected to doctor sweetening, said stock having incorporated'the necessary amount of added free sulfur for :the treatment. vThe sour distillate is passed by pump 2-through line 3 into the orifice mixer 4 wherein it is intimately mixed with doctor solution, `ledinto line 3 from line 5 by pump 6. The =orice -mixer is equipped internally with orifices-'latgspaced pointsY for obtaining agita- 2i. y j

tion and intimate mixing. From the orifice mixer, the doctor sweetening reaction mixture is led by line 8 to the settler 9 wherein spent doctor reagent is settledv to the bottom to be withdrawn through line i0 and 'control valve Il to'cutlet line I2. For further removal of spent doctor reagent, the sweetening reaction mixture' is led from the first settler E through line i3 into a second settlerlll wherein the settling. operation is repeated, alloi the settled d'oct'or reagent being removed from the settler through'line I5 and,

control valve it to be withdrawn from the system by line l2, which may be used tot, V spent doctor solution to a sodiumplumbitere; generating unit (not shownl.' Itii'sitobe nudeln-lj stood that the described part of 'the doctorl sweetening operation may be carried out in units.

of Various forms, such as areifconverrtionalforiz" otherwise.

The sweetened oil, following the'separatibrroi the spent doctor'reagent with thegmajor part; of.

the lead sulfide, still retainszacertainesn-'fallr Vamount 'of nelyf divided lead; sulderin suspension. This product ispassed from the nal settling Zone to the washing"unit,"as illustrated in thev drawing,.by. being-led rom.the secondsettler M1 throughl line? 111' intofan. orifiea; mixer` tit; to: whichfis: simultaneously fed. tliewashing-fliquidY or solutionl from inlet line". 2151051 pump=22gand a" desired amountk of' recirculatedf or: used; washing liquid` from'line Z3: .'I'helmixture; of the d'octor" 1 sweetened oilfand washing solution is discharfgedv froml-th'efmixer vvia. line'. t9A into ai settler': 2.0;v wherein the washing. solution;v and; lead suld'ejisf settled to the bottomyand thelsweetenechydrozcarbon oil substantially. freedi of: lead` vsul'vdeir is:v withdrawnffrom/an upper..r stratum; through line 24.' "The settled' aqueous-layer? isswithdrawn from "the bottom of settlerflthronglr lineS'Z'Vand any'amount Vtl'iereof may be: led) through *valve 26" 'into"line AZSfor .recirculatten.V as mentioned. portion. of thee. withdrawn. settled?. aqueous;

in the lead sulde separation is very small, beingA v of theorder of from about 0.005% -to 0.1% by weight and preferably in the range of 0.01% ,to

0.08% (from about 10 mg. to 80 mg./100 m1; of aqueousy solution) There are a number of'modii'lcations which may be made in the thiazole salt compositiony used in accordance with the present invention,

carbon-oil-yet-solubleinwater. The thiazfole salt. settling. agents hereinsdgf scribed mayfbe used in variouspmodicationset the doctortreatment.. 'Iheyimay befused'where I sweetening is. conducteclina, .batchsystem ordm' a continuous-. procedu1je, as described?,

vbe employediQ-'0btain-m0rerapidand--comrletef separationof thesuspended metalsulide when leadsnlde is-usedbyitselfi asasweeteningagent;vl

or withsome o therrmetall compound. -IthaslbeefnL 'f ,found-thatthe-'thiaaole salt agentsfare b eneoiafliVv inobtaininganeutral iinishedflistillatesB/tlsfaf tollyfreei leadsulde.v harina@ very ged ape pearance and withadesirablejreductiorrin-,sultupz 2 content Vand even of gum-forming constituer'itsf.:I Tests have further! demonstrated thatrin;eddie-j` eningthef settling; period;k the thi-azole .saltsolu-q Vtion to accelerating-the. separationfend-.shoxtqfy tionsyare superior torother vtypes of' af'llw' v solutions commonly employed'asfis illustrated the following.: test. data; y

` 1 Pbs was in a caguiated form.

solution may be led yty linezatiiugh ofriedf valve` 2l" into a suitable unit for separa tjiorrVr andi Vrecoveifypf lead' sul'de from thel aqueoussolution, and theV thus recovered lead" snildemay' b eused for regeneration* 'i1-1to1 sodiumfplimbite, A or doctor reagent. l -;v

vIn the desicrilgzedlV plant operation'',Y the desired Y concentration of -thiazol'e-fsaltjis maintained? in` tlrewashingVV solution byV addi-tien or the ne'ces saryY Vamount of the salt to the fresh?l waterv eharged-- into the washing? unit through liner-2|.

" yln`general, the-- washi treatmentiis carriedoutjin the vicinity ofgatmospheric'pressurelor under slightly elevated?-pressuresl ranging-up to arent A3o 1bs /sq.jin gaugeandl under? moderate temperatures varyingfrem about" 305Y tol-120 F., which is in a-inl'yf` dependent Auponi atmospheric conditionallhefamount off the-fthiazole salt which-may? be solution for makingv al considerable improvement distillate 011 containingfmeraptans fono'wingitte dispersion of finely-*divided metal sulildesi'ri-ftl'fie? y sweetened distillate product, the step comprising-: separatingfsaidmetalfsuiiides from the oil by j -1 wash-ingwith anaqueoussolution; containing :1\" f v smallgconcentration Yofamercaptoaryl thiazioleY saltof a substance selected :from the=group 'f sisting oi alkali metals,',-alkaline'r earth metals f and theqammonium radicalqwhich ,isf .s ubstan tiallyinsoluble'in the-hydrocarbonjo" 2. In the process of sweetening ahydrocarbxm.

distillate oil bya doctor'treatingf agentfitheistesl y of removing nal traces of lead sulifide `fromthe doctor sweetened oil consisting in washing the l sweetened oil with Water containing in small concentration an' alkalirmetal'salt of a mercapto-v V 3. In the process of s weeteninga sour petxjo- 7.5i leum distillate by a` doc-tor' solutionfo alkaline sodium 'plumbitathe step of removing the final traces of lead sulfide from the sweetened oil which comprises washing the sweetened oil with water containing about 0.005% `to about 0.1%

the sodium salt of mercaptobenzeolead sulde which comprises addingrt'o water used l in the washing a small*V amount of a mercaptoaryl thiazole salt the cation of which forms hy-A droxides soluble in water. y v Y 5. In the process of sweetening asour' hydrothiazole.'

Vcarbon distillate by a doctor solution of alkaline n sodium plumbite, the step of removing the nal traces of lead sulfide from thel sweetened oil which comprises washing the sweetened oil with water containing about 0.005% to about 0.1% by weight of the potassium salt of mercapto-benzo- 6. In the process of sweetening a sour hydrocarbon distillate by a doctor solution of alkaline sodium plumbite, the step ofremoving the final traces of lead sulfide from the sweetened oil which comprises washing the sweetened oil with i5 benzo-thiazole.

water containing about 0.005% to about 0.1% by w weight of the ammonium salt of mercapto- I-IEN'RY C. PAULSEN. 

